Find the area of an equilateral triangle (regular 3-gon) with the given measurement.

9-inch perimeter

A = sq. in.

Since all sides of an equilateral triangle are equal

so let all sides are x inches

perimeter=9 in.

x+x+x=9

3x=9

x=9/3

x=3 in.

so area of triangle=squareroot3/4*side^2

Area=squareroot3/4*3^2

=squareroot3/4*9

So area is squareroot3/4*9 square in